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2.3 – Carbon Compounds

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Carbon

§  has 4 valence electrons which can bond covalently with other atoms

§  can bond with other carbon atoms to form long chains §  can form single, double, or triple bonds… §  …can form a great variety of giant and complex

molecules

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The Chemistry of Carbon

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§  96% of living organisms is made of: n  carbon (C) n  oxygen (O) n  hydrogen (H) n  nitrogen (N)

Elements of Life

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Molecules of Life §  Put C, H, O, N together in

different ways to build living organisms

§  What are bodies made of -  carbohydrates -  proteins -  fats (lipids) -  nucleic acids

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How do we make these molecules?

We build them!

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Building large molecules of life §  Chain together smaller molecules called monomers

(mono = one, meris = part)

to make bigger molecules called polymers

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§  Small molecules = building blocks

§  Bond them together = polymers

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Building important polymers

sugar – sugar – sugar – sugar – sugar – sugar

nucleotide – nucleotide – nucleotide – nucleotide

Carbohydrates = built from sugars

Proteins = built from amino acids

Nucleic acids (DNA) = built from nucleotides

amino acid

amino acid – amino

acid – amino acid – amino

acid – amino acid –

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Carbohydrates

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Low-Carb vs. Low-Fat

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§  General formula: Cn(H20)n

§  Building block molecules =

sugar sugar sugar sugar sugar sugar sugar sugar

sugar - sugar - sugar - sugar - sugar

sugars

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Building carbohydrates

| glucose

| glucose

1 sugar = monosaccharide

2 sugars = disaccharide

| maltose

mono = one

saccharide = sugar di = two

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| fructose

| glucose

1 sugar = monosaccharide

| sucrose

(table sugar)

2 sugars = disaccharide

How sweet

it is!

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BIG carbohydrates Polysaccharides

§  Starch (energy storage in plants)

§  Glycogen (energy storage in in liver and muscles of animals)

§  Cellulose (structure in plants, cell walls)

§  Chitin (structure in arthropods and fungi)

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Building BIG carbohydrates glucose + glucose + glucose… =

starch (plant)

glycogen (animal)

energy storage

polysaccharide

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Polysaccharides §  cost energy to build §  So why build them? §  use as energy reserves

(starch in plants, glycogen in animals)

vs.

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Cellulose §  Most abundant

organic compound on Earth (~100 billion tons/year)

§  makes up cell wall in plants, wood, paper…

§  Herbivores have evolved a mechanism to digest cellulose. Most carnivores cannot.

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Helpful bacteria §  How can cows digest cellulose so well? §  Bacteria live in their stomachs and help digest

cellulose-rich (grass) meals

Eeeew… Chewing cud?

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Benefits of Cellulose

or

§  Cellulose/fiber stays undigested and keeps material moving in your intestines

§  So eat your fiber or else….

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Lipids

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Lipids §  are hydrocarbons (made from

carbon and hydrogen atoms) §  Include

-  Fats

-  oils

- waxes

-  hormones (sex hormones)

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§  Functions: -  energy storage

very concentrated twice the energy as carbohydrates!

-  cell membrane -  insulates body -  cushions organs

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… as cushion

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Structure of Fat NOT a chain of monomers (polymer) = just a “big fat molecule”

§  contains a glycerol molecule and 3 fatty acid tails

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Saturated fats §  Fatty acid tails contain

only single C-C bonds §  “saturated” means

maximum amount of H’s

§  are solid at room temperature

§  should limit the amount of saturated fat in your diet since it contributes to heart disease, deposits in arteries, etc.

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Unsaturated fats §  Fatty acid tails contain at

least one C-C double bond (monounsaturated) or multiple double bonds (polyunsaturated)

§  are liquid at room temp. since fatty tails don’t stack tightly together

§  include plant, vegetable and fish fats

§  are healthier choices in your diet

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Saturated vs. Unsaturated

ü

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Hydrogenated Oil

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Twinkies

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7 Food Rules

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Yum, yum, yum… and hydrogenated fat!

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Trans Fat

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California Bans Trans Fat

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Other lipids in biology §  Cell membranes are made out of lipids §  forms a barrier between the cell and the outside

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Proteins

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Proteins

insulin

§  muscle

§  skin, hair, fingernails, claws §  Pepsin (digestive enzyme

in stomach)

§  Insulin (hormone that controls blood sugar levels)

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§  many, many functions §  enzymes -  help to speed up chemical

reactions Ex: protease in detergents

§  hormones - signals from one body

system to another (insulin) §  movement - muscle

§  immune system -  protect against germs

Functions

insulin

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§  Building block =

amino acid

amino acid – amino

acid – amino acid – amino

acid –

—N— H

H

H |

—C— |

C—OH || O

variable group

amino acids

There’s 20 of us…

like 20 different letters in an alphabet!

Can make lots of different

words

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Amino acids §  Structure -  central carbon -  amino group -  carboxyl group (acid) -  R group (side chain)

§  variable group §  different for each amino acid §  confers unique chemical

properties to each amino acid (like 20 different letters of the alphabet)

—N— H

H

C—OH || O

R

|

—C— |

H

Oh, I get it! amino = NH2 acid = COOH

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Effect of different R groups: Nonpolar amino acids

Why are these nonpolar and hydrophobic?

§  nonpolar and hydrophobic

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Effect of different R groups: Polar amino acids

§  polar or charged and hydrophilic

Why are these polar and hydrophilic?

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Amino acid chains §  Proteins = amino acids chained into a polymer

§  Each amino acid is different -  some “like” water and dissolve in it -  some “fear” water and separate from it

amino acid amino acid amino acid amino acid amino acid

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For Proteins: SHAPE matters! §  Proteins fold and twist into 3-D shape

§  Different shapes = different jobs

hemoglobin

growth hormone

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It’s SHAPE that matters! §  Proteins’ SHAPE determines their

JOB §  Unfolding – denaturing – a protein

destroys its shape, often prevents it from doing its job

§  Protein denaturation can occur due to changes in:

- temperature - pH (acidity)

folded

unfolded “denatured”

In Biology, it’s not the size, it’s the SHAPE that matters!

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Any Questions?

Penguins gone bad!